If you enable either File Sharing (AFP or SMB), Mac OS X 10.5.6 will have not only the AFP or SMB ports, but also port TCP/88 open. The daemon on this port is kdcmond(8), which is described as “KDC monitoring daemon – Open Directory Single Sign On”. Most people who are not connected to a Mac OS X Server-based network probably don't need this service.

If you would like to disable this daemon, you need to change the launchd(8) configuration, which is accomplished by this one-liner:

• Disable:

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.kdcmond.plist

• Enable:

sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.kdcmond.plist

Note that these commands edit the above files, implying that the effects may be undone by future updates from Apple.